This invention generally relates to the preparation and use of tetraazido polyesters. Solid propellants, gun propellants, and explosives are generally composed of oxidizers, binders, plasticizers, and sometimes a fuel. The oxidizers such as ammonium perchlorate and HMX are well known to the art. Hydrocarbon binders and inert plasticizers such as dioctyl phthalate, and triacetin are generally used. Recently, attempts have been made to replace the inert plasticizers with energetic materials so as to increase the overall energy of the propellant.
Organic high nitrogen compounds are useful ingredients of solid propellants for guns, rockets, and gas generator compositions. Their main combustion product is nitrogen, which is an extremely stable molecule that shows little tendency to react even at the high temperatures that exist in gun tubes and rocket engines. Additionally, nitrogen is completely transparent in the infrared and so contributes no interference to missile guidance systems using infrared radiation.
One way of making a compound high in nitrogen is to introduce several azido (N.sub.3) groups into the molecule. The most attractive feature of azido compounds is their high heats of formation. The azido groups contributes a positive heat of formation of about 85 kcal/unit. This high contribution of the azido group to the heat of formation is most clearly evident from a comparison of ethanol and 2-azidoethanol. The heat of formation of ethanol is -66 keal/mole, while 2-azidoethanol has a heat of formation of +22.5 keal/mole. The heat of formulation of the tetraazido polyesters is equally high. Thus, the energy content of azido compounds is readily evident. The key to the practical utilization of azido compounds is to tailor their molecular structure to take advantage of the high energy content of the azido moeity and still have acceptable properties in terms of insensitivity and good thermal stability.
The simplest composition contemplated by this invention is merely a mixture of a tetraazido polyester and nitrocellulose. A composition such as this when used as a gun propellant serves to increase impetus without increasing the flame temperature significantly by virtue of the fact that this composition produces more gas per unit weight on decomposition than a typical double-base composition of nitrocellulose-nitroglycerin propellant.